Plot the surface as well

src/test_circle_1.m

+clear all;
+
 if exist('graphics_toolkit','file')
   graphics_toolkit('fltk')
 end
@@ -16,11 +18,21 @@ y = scale*sin(t);
 z = arrayfun(@(vec1, vec2) J([vec1; vec2]), x, y);
 
 hold on
-plot3(x,y,z);
+plot3(x,y,z,'k');
 
 title 'scale = 1'
 
 # Minimum taken from test-circle.cc with scale=1
 
 plot3(-1.487905e-01, +9.888687e-01, J([-1.487905e-01; +9.888687e-01]), 'r+');
-hold off
+
+x = scale * (-1:.05:1);
+y = scale * (-1:.05:1);
+[X, Y] = meshgrid(x,y);
+
+for i=1:length(y)
+  val(i,:) = arrayfun(@(vec1, vec2) J([vec1; vec2]), X(i,:), Y(i,:));
+end
+
+surf(x, y, val)
+hold off;

src/test_circle_10.m

+clear all;
+
 if exist('graphics_toolkit','file')
   graphics_toolkit('fltk')
 end
@@ -15,7 +17,8 @@ x = scale*cos(t);
 y = scale*sin(t);
 z = arrayfun(@(vec1, vec2) J([vec1; vec2]), x, y);
 
-plot3(x,y,z);
+hold on
+plot3(x,y,z,'k');
 
 title 'scale = 10'
 
@@ -24,3 +27,14 @@ title 'scale = 10'
 line([-5.3444 6.36022],
      [8.45206 -7.71671],
      [J([-5.3444; 8.45206]) J([6.36022; -7.71671])])
+
+x = scale * (-1:.05:1);
+y = scale * (-1:.05:1);
+[X, Y] = meshgrid(x,y);
+
+for i=1:length(y)
+  val(i,:) = arrayfun(@(vec1, vec2) J([vec1; vec2]), X(i,:), Y(i,:));
+end
+
+surf(x, y, val)
+hold off;